The overall objective of our studies is to understand the manner in which the genetic information of mammalian cells is expressed and regulated. Our immediate goal is to describe the steps involved in the synthesis of messenger RNA in the nucleus and any modification that it may undergo before being expressed in the cytoplasm as well as its fate during and after translation. During the upcoming year, we propose to study the fate of the poly(A) region of the alpha- and beta-globin mRNAs. Previous studies suggest that 150 adenylic acid residues are added to globin mRNA soon after its synthesis and that these are removed in a specific manner giving rise to discrete poly(A) sizes during translation. The fate of the poly(A) region will be examined in pulse-chase studies using nucleated erythroid cells from the spleens of anemic mice. Also, using nucleated erythroid cells of mice, incorporation of methyl groups or other modified nucleotides into the alpha- and beta-globin mRNAs will be followed. In addition, the half-life of the alpha- and beta-globin mRNAs in DMSO induced erythroleukemic cells, a cell line transformed by Friends leukemia virus, will be determined.